Microspheres containing anthelmintic macrocyclic lactones

Abstract

Disclosed are microspheres containing 1% to 20% by weight of milbemycin, avermectin or a derivative thereof, 50% to 95% by weight of a fat, a wax or a mixture thereof, 0.1% to 10% by weight of a steroid lipid, preferably cholesterol, and 0.01% to 1% by weight of an antioxidant.

The invention claimed is: 
     
       1. Microspheres containing 1 to 20% milbemycin, avermectin or a derivative thereof, 50% to 95% by weight of a fat or a wax or a mixture thereof, 0.1% to 10% by weight of cholesterol, and 0.01 to 1% by weight of an antioxidant, said microspheres being prepared by solubilizing said milbemycin, said avermectin or said derivative thereof, in said fat, said wax, or said mixture thereof. 
     
     
       2. Microspheres according to  claim 1  wherein the milbemycin derivative is moxidectin, present in amounts ranging from 1 to 15%. 
     
     
       3. Microspheres according to  claim 1  containing 60 to 90% by weight of a fat or wax or a mixture thereof. 
     
     
       4. Microspheres according to  claims 1 , wherein the fat or wax is a fatty acid ester. 
     
     
       5. Microspheres according to  claim 4  wherein the fat is glyceryl tristearate. 
     
     
       6. Microspheres according to  claim 1  wherein cholesterol is present in amounts ranging from 0.1 to 5% by weight. 
     
     
       7. Microspheres according to  claim 1  containing 0.01 to 0.5% by weight of an antioxidant. 
     
     
       8. Microspheres according to  claim 1  wherein the diameter of the microspheres is lower than 800 μm. 
     
     
       9. Pharmaceutical formulations for parenteral administration, comprising the microspheres of  claim 1  and an aqueous carrier suitable for parenteral administration to animals. 
     
     
       10. Method of preventing or treating diseases due to helminths, nematodes and endo- or ecto- parasites in warm-blooded animals with the formulations of  claim 9 , said method comprising
 admininstering an effective amount of said formulations to said warm-blooded animals; and 
 preventing or treating said diseases.